Conversion of hydrocarbon oils



March 15, J C MQRRELL CONVERSION. OF HYDROCARBON OILS Filed Jan. 30,1936 IH PH I l INVENTOR JACQUE C. MORRELL TORNEY Patented Mar. 15, 1938UNITED STATES PATENT OFFICE CONVERSION OF HYDROCARBON OILS Application"January 30, 1936, Serial No. 61,489

6 Claims.

This invention particularly refers to an improved process for theselective conversion of rel atively low-boiling and high-boilinghydrocarbon oils wherein liquid products resultingfrom conversion of therelatively heavy intermediate liquid conversion products and chargingstock as well as, when desired, of the relatively low-boilingintermediate liquid conversion products are subjected to continuedheating under independently controlled cracking conditions regulated toeifect their subsequent coking or to materially reduce their viscositywithout substantial coke formation.

In one embodiment, the invention comprises subjecting hydrocarbon oil toconversion conditions of cracking temperature and superatmosphericpressure in a heating coil and communieating enlarged reaction chamber,separately withdrawing vaporous and liquid conversion n products fromthe reaction chamber, passing the latter through a separate heating coilwherein they are quickly heated to a high conversion temperature undernon-coking conditions, intro ducing the heated products from saidseparate heating coil into a separate enlarged chamber wherein theirhigh-boiling components are reduced to coke, subjecting the vaporousconversion products, including those evolved from the materialsundergoing coking, to fractionation whereby their components boilingabove the range of the desired final light distillate conversion productof the process are condensed as reflux condensate, subjectingfractionated vapors of the desired end-boiling point to condensation,re- 53,; covering the resulting distillate, separating the refluxcondensate formed by said fractionation into selected relativelylow-boiling and highboiling fractions, returning the latter to the firstmentioned heating coil for further conversion, subjecting said selectedlow-boiling fractions of the reflux condensate to further conversionunder independently controlled temperature and pressure conditions in aseparate heating-coil, and introducing the resulting heated productsinto either the reaction chamber or the coking chamber or in part toboth.

As an alternative method of operation to that above described, thecracking conditions employed in said separate heating coil to which theliquid conversion products from the reaction chamber are supplied may beregulated to effect a substantial reduction in their viscosity withoutexcessive conversion and without appreciable coking, in which case theenlarged chamber to which the products from this heating coil aresupplied functions as a vaporizing and separating chamber from whichnon-vaporous residual liquid is withdrawn-to cooling and storage orelsewhere, as desired, while the vapors evolved in this zone pass tofractionation together with the other vaporous conversion products ofthe process.

The features and advantages of the invention as well as variousalternative methods of operation of the process will be more apparentwith reference to the accompanying diagrammatic drawing and thefollowing description thereof. It will be understood, of course, thatthe various alternative methods of operation are not to be consideredequivalent but may be selected to suit requirements depending primarilyupon the type of charging stock employed and the desired re sults. Thedrawing illustrates one specific form of apparatus embodying thefeatures of the invention and in which the various alternative methodsof operation may be accomplished.

Referring to the drawing, hydrocarbon oil charging stock for the processis supplied through line I and valve 2 to pump 3 and, in the particularcase here illustrated, is directed through line 4, valve 5 and line B toconversion in heating coil 1 or it may be diverted from line 4 anddirected through line 8, valve 9 and line H) to conversion in heatingcoil ll. When the charging stock comprises an oil of relativelyhigh-boiling characteristics it is preferably supplied to heating coil 1and, on the other hand, when it comprises an oil of relativelylow-boiling characteristics it is preferably supplied to heating coilll. It is, of course, entirely within the scope of the invention topreheat the charging stock by any well known means, not illustrated, toany desired temperature below that at which its appreciable conversionwill occur, prior to its introduction into the system. It is alsospecifically within the scope of the invention, when desired, andparticularly in case the charging stock comprises an oil of relativelywide boiling range, to introduce the same all or in part intofractionator 30, by well known means, not illustrated, wherein itcommingles with the vaporous conversion products undergoingfractionation and is separated, together with the reflux condensateformed in this zone, into selected relatively lowboiling andhigh-boiling fractions which are supplied, respectively, to heatingcoils II and I, as will be later more fully described.

A furnace l2 of suitable form supplies the required heat to the oilpassing through heating coil 'l'to subject the same to the desiredconversion temperature, preferably at a substantial superatmosphericpressure, and the heated products are discharged through line 53 andvalve it into reaction chamber I5.

Chamber I5 is also preferably maintained at a substantialsuperatmospheric pressure and, although not indicated in the drawing,this zone is preferably insulated in order to conserve heat so that theheated products supplied to this zone, and more particularly theirvaporous components, are subjected to continued conversion therein.vaporous conversion products and nonvaporous residual liquids areseparated in chamber i5, the vapors being withdrawn from any desiredpoint or plurality of points in the chamber above the point of removalof the liquid conversion products and in the case here illustrated theyare directed through line i6, valve I? and line it into chamber l9.However, when desired, all or regulated portions of the vaporousconversion products thus withdrawn from chamber l5 may be supplieddirectly to fractionator 30 by well known means, not illustrated.

The non-vaporous liquid conversion products are withdrawn from the lowerportion of chamber l5 and are directed through line 20 and valve 2! tofurther conversion in heating coil 22 which is supplied with therequired heat from a suitable furnace 23 and from which the heatedproducts are discharged through line 24 and valve 25 into chamber I9.

As previously mentioned, the invention contemplates two alternativemethods of operation with respect to the conditions employed in heatingcoil 22 and chamber I9. In case it is desired to operate the process forthe production of coke as the final residual product of the process theoil passing through heating coil 22 is rapidly heated to a relativelyhigh conversion temperature sufficient to insure its subsequentreduction to coke in chamber IS without allowing it to remain in theheating coil for a sufiicient length of time to permit any appreciableformation and deposition of coke in this zone or in the communicatinglines. In case it is desired to operate the process for the productionof good quality liquid residue the conversion conditions employed inheating coil 22 are of a relatively mild nature which will effect asubstantial reduction in the viscosity of the relatively heavy oilsupplied to this zone without excessive conversion and without anyappreciable formation of coke.

Chamber I9 is preferably operated at a substantially reduced pressurerelative to that employed in chamber I5 in order to assist vaporizationof the heated products supplied thereto from heating coil 22. Whenchamber I9 is operated for the production of coke the coke may beallowed to accumulate within the chamber until it is substantiallyfilled, or until the operation of the chamber has been completed for anyother reason, following which it may be removed in any well knownmanner, not illustrated, and the chamber prepared for further operation.It

is, of course, within the scope of the invention to employ a pluralityof such chambers for the deposition of coke in which case theypreferably are alternately operated, cleaned and prepared for furtheroperation in order that the coking stage, in common with the rest of thesystem, may be operated continuously. Line 26 controlled by valve 21serves as a means of removing non-vaporous liquid residue from chamberl9 when this zone is operated for the production of residual liquid.This line may also serve as 2.

drain-line and, when desired, as a means of introducing steam, water orother suitable cooling material into the chamber, particularly whenoperated as a coking zone, after operation of the chamber has beencompleted and after it has been isolated from the rest of the system, inorder to hasten cooling and facilitate removal of the coke. Vaporsevolved in chamber l9 as well as any vaporous products supplied to thiszone from chamber l5 and/or from heating coil II are withdrawn from theupper portion thereof and directed through line 28 and valve 29 tofractionation in fractionator 30 together with any vaporous productssupplied directly to the fractionator from chamber i5, as previouslymentioned.

The components of the vaporous conversion products supplied tofractionator 30 boiling above the range of the desired final lightdistillate conversion product of the process are condensed in this zoneas reflux condensate and the reflux condensate, together with anycharging stock of relatively wide boiling range which may be supplied tothe fractionator as previously mentioned, is separated into selectedrelatively low-boiling and high-boiling fractions. Fractionated vaporsof the desired end-boiling point, preferably comprising materials withinthe boiling range of motor fuel and of good antiknock value, arewithdrawn from the upper portion of the fractionator, together withuncondensable gas produced by the operation, and directed through line3| and valve 32 to condensation and. cooling in condenser 33. Theresulting distillate and gas passes through line 34 and valve 35 tocollection and separation in receiver 36. Uncondensable gas may bereleased from the receiver through line 31 and valve 38. Distillate maybe withdrawn from the receiver through line 39 and valve 40 to storageor to any desired further treatment. When desired, regulated quantitiesof the distillate col lected in receiver 35 may be recirculated by wellknown means, not illustrated in the drawing. into the upper portion offractionator 30 to serve as a refluxing and cooling medium in this zonefor assisting fractionation of the vapors and to maintain the desiredvapor outlet temperature therefrom.

The high-boiling fractions of the reflux condensate formed infractionator 33 are withdrawn from the lower portion of this zonethrough line H and valve 42 to pump 43 by means of which they arereturned through line 6 and valve 44 to further conversion in heatingcoil 1.

The selected low-boiling fractions of the reflux condensate formed infractionator 38 are withdrawn from one or a plurality of suitableintermediate points in this zone, provision being made in the case hereillustrated for removing the same from the fractionator through line G5wherein they are directed through valve 46 to pump dl and are thencesupplied through line H] and valve at to further conversion in heatingcoil II.

The relatively low-boiling oil supplied to heating coil H is subjectedtherein to the desired conversion temperature by means of heat suppliedfrom a furnace 49 of suitable form. Preferably a substantialsuperatmospheric pressure is maintained at the outlet from heating coilll although, when desired, lower pressures down to substantiallyatmospheric may be employed in his zone. The heated products aredischarged from heating coil II through line 50 and may be thencedirected, all or in part, through line 5| and valve 52 into reactionchamber l5, wherein they are subjected to continued conversion, together with the heated products from heating coil 1, or they may pass,all or in part, through valve 53 in line 50 into chamber l9, enteringthis zone, in the case here illustrated, through line l8 although theymay be introduced thereto at any other desired point or plurality ofpoints in this zone.

The range of operating conditions which may be employed to accomplishthe various objects of the invention is approximately as follows:

The heating coil to which the relatively highboiling fractions of thereflux condensate are supplied may utilize an outlet conversiontemperature ranging, for example, from 825 to 950 F. preferably with asuperatmospheric pressure at this point in the system of from to 500pounds, or more, per square inch. The heating coil to which therelatively low-boiling fractions of the reflux condensate are suppliedmay employ an outlet conversion temperature ranging, for example, from900 to 1050 F. with any deired pressure ranging from substantiallyatmospheric to a superatmospheric pressure of from 800 pounds, or more,per square inch. Ordinarily temperatures of from 975 to 1050 F. areutilized when relatively low pressures are employed in this zone whilerelatively high superatmospheric pressures are preferred when mildertemperature conditions are employed. The reaction chamber is preferablyoperated at a substantial superatmospheric pressure which may besubstantially the same or somewhat lower than that employed at theoutlet from the heating coil to which the relatively high-boiling refluxcondensate is supplied. .In case a higher pressure is employed in thereaction chamber than that maintained at the outlet from the heatingcoil to which the relatively low-boiling reflux condensate is suppliedthe conversion products from this heating coil are preferably allsupplied to the vaporizing or coking chamber. When the process isoperated for the production of coke as the final residual product of theprocess the heating coil to which the residual liquid conversionproducts from the reaction chamber are supplied preferably employs anoutlet conversion temperature of the order of 900 to 1000 F. with anydesired pressure ranging from substantially the same as that employed inthe reaction chamber down to substantially atmospheric pressure. Whenthe process is operated for the production of liquid residue the heatingcoil to which the liquid conversion products from the reaction chamberare supplied preferably employs a relatively mild cracking temperatureof the order of 760 to 850 F. preferably with a superatmosphericpressure measured at the outlet from this zone of from 100 to 500pounds, or thereabouts, per square inch. The vaporizing or cokingchamber may be operated at any desired pressure ranging fromsubstantially the same as that employed at the outlet from thecommunicating heating coil down to substantially atmospheric pressureand this zone is preferably maintained at a substantially reducedpressure relative to that employed in the reaction chamber ranging forexample, from substantially atmospheric to 150 pounds, or thereabouts,per square inch superatmospheric pressure. The fractionating condensingand collecting portions of the system may employ pressures substantiallythe same or somewhat lower'than the pressure employed in the vaporizingand coking chamber.

As a specific example of the operating conditions and the resultsobtainable by one method of operation of the process in an apparatussuch as illustrated and above described; the charging stock, whichcomprises an 18 A. P. I. gravity Mid-Continent straight-run residualoil, is subjected, together with high-boiling fractions of the refluxcondensate, to a conversion temperature, measured at the outlet from theheating coil to which this material is sup-plied, of approximately 890F. with a superatmospheric pressure at this point in the system of about300 pounds per square inch and substantially the same pressure isemployed in the reaction chamber. The relatively low-boiling fractionsof the reflux condensate, approximately 90 per cent of which boil withinthe range of 400 to 600 F., are subjected in a separate heating coil toan outlet conversion temperature of approximately 950 F. at asuperatmospheric pressure of about 500 pounds per square inch. About 65per cent of the heated products from the light oil heating coil areintroduced into the reaction chamber and the remainder'are supplied tothe lower portion of the coking zone. Vaporous and liquid conversionproducts are separately withdrawn from the reaction chamber, the vaporsbeing supplied to the coking chamber while the liquid conversionproducts are quickly heated in a separate heating coil to an outletconversion temperature of approximately 970 F. at a superatmosphericpressure of about 50 pounds per square inch and the heated products areintroduced into the coking chamber, which is maintained at subpounds ofpetroleum coke of relatively low.

volatility and of good structural strength, the remainder beingchargeable, principally to uncondensable gas.

As an illustration of another specific operation of the process; theoperating conditions are similar to that above described with thefollowing exceptions: The liquid conversion products from the reactionchamber are subjected in the heating coil to which they are supplied tocontinued relatively mild conversion at a maximum.

temperature of approximately 810 F. and a superatmospheric pressure ofabout pounds per square inch, this pressure being substantiallyequalized in the succeeding vaporizing chamber.

The temperature employed in the heating coil to which the charging stockand relatively heavy fractions of the reflux condensate are supplied isapproximately 850 F. and the total heated products from the light oilheating coil are introduced into the reaction chamber. In this operationthere is produced, per barrel of charging stock, approximately 56 percent of 400 F. endpoint motor fuel having an octane number ofapproximately 66 and approximately 35 per cent of good quality liquidresidue meeting market specifications for premium fuel oil, theremainder being chargeable, principally, to uncondensable gas.

I claim as my invention:

1. In a process for the conversion of hydrocarbon 011$,Wh91'911'1 an oilof relatively highi boiling characteristics is subjected to conversionconditions of cracking temperature and superatmospheric pressure in aheating coil and communicating reaction chamber, vaporous and liquidconversion products separately withdrawn from the reaction chamber andthe former subjected to fractionation, the improvement which comprisessubjecting said liquid conversion products withdrawn from the reactionchamber to continued conversion under independently controlled heatingconditions in a separate heating coil, introducing the resulting heatedproducts into a separate enlarged chamber wherein vaporous andnon-vaporous conversion products are separated, subjecting the former tosaidfractionation whereby their insufficiently converted com ponents arecondensed as reflux condensate and separated into selected relativelylow-boiling and high-boiling fractions, subjecting fractionated vaporsof the desired end-boiling point to condensation, recovering theresulting distillate, returning said high-boiling fractions of thereflux condensate to the first mentioned heating coil for furtherconversion, subjecting said low-boiling fractions of the refluxcondensate to independently controlled conversion conditions of crackingtemperature and superatmospheric pressure in a separate heating coil,and introducing the resulting heated products into said reactionchamber.

2. In a process for the conversion of hydrocarbon oils, wherein an oilof relatively highboiling characteristics is subjected to conversionconditions of cracking temperature and superatmospheric pressure in aheating coil and communicating reaction chamber, vaporous and liquidconversion products separately withdrawn from the reaction chamber andthe former subjected to fractionation, the improvement which comprisessubjecting said liquid conversion products withdrawn from the reactionchamber to continued conversion at a relatively mild crackingtemperature and substantial superatmospheric pressure in a separateheating coil whereby to materially reduce their viscosity withoutexcessive conversion thereof and without appreciable coke formation,introducing the heated products from said separate heating coil into avaporizing and separating chamber maintained at a substantially reducedpressure relative to that employed in the reaction chamber, recoveringnonvaporous residual liquid from the vaporizing and separating chamber,separately removing the vaporous conversion products therefrom andsubjecting the same to said fractionation for the formation of refluxcondensate, subjecting fractionated vapors of the desired end-boilingpoint to condensation, recovering the resulting distillate, separatingthe reflux condensate formed by said fractionation into selectedrelatively low boiling and high-boiling fractions, returning saidhigh-boiling fractions to the first mentioned heating coil for furtherconversion under independently controlled temperature and pressureconditions, subjecting said low-boiling fractions of the refluxcondensate to independently controlled conversion conditions oftemperature and superatmospheric pressure in a separate heating coil,and introducing at least a portion of the resulting heated products intothe reaction chamber.

3. In a process for the conversion of hydrocarbon oils, wherein an oilof relatively highboiling characteristics is subjected to conversionconditions of cracking temperature and superatmospheric pressure in aheating coil and communicating reaction chamber, vaporous and liquidconversion products separately withdrawn from the reaction chamber andthe former subjected to fractionation, the improvement which comprisessubjecting said liquid conversion products withdrawn from the reactionchamber to continued conversion at a relatively mild crackingtemperature and substantial superatmospheric pressure in a separateheating coil whereby to materially reduce their viscosity withoutexcessive conversion thereof and without appreciable coke formation,introducing the heated products from said separate heating coil into avaporizing and separating chamber maintained at a substantially reducedpressure relative to that employed in the reaction chamber, recoveringnon-vaporous residual liquid from the vaporizing and separating chamber,separately removing the vaporous conversion products therefrom andsubjecting the same to said fractionation for the formation of refluxcondensate, subjecting fractionated vapors of the desired endboilingpoint to condensation, recovering the resulting distillate, separatingthe reflux condensate formed by said fractionation into selectedrelatively low-boiling and high-boiling fractions, returning saidhigh-boiling fractions to the first-mentioned heating coil for furtherconversion, subjecting said low-boiling fractions to further conversionunder independently controlled temperature and pressure conditions in aseparate heating coil, and introducing at least a portion of theresulting heated products into the vaporizing and separating chamber.

4. A process such as claimed in claim 2, wherein the remainder of theheated products from the last mentioned heating coil is introduced intothe vaporizing and separating chamber.

5. In a process for the conversion of hydrocarbon oils, wherein an oilof relatively highboiling characteristics is subjected to conversionconditions of cracking temperature and superatmospheric pressure in aheating coil and communicating reaction chamber, vaporous and liquidconversion products separately withdrawn from the reaction chamber andthe former subjected to fractionation, the improvement which comprisesheating the liquid conversion products withdrawn from the reactionchamber to a relatively high conversion temperature under noncokingconditions in a separate heating coil, introducing the highly heatedproducts into a coking chamber wherein their high-boiling components arereduced to coke, removing vaporous conversion products from the cokingchamber, subjecting the same to said fractionation for the formation ofreflux condensate, subjecting fractionated vapors of the desiredend-boiling point to condensation, recovering the resulting distillate,separating the reflux condensate formed by said fractionation intoselected relatively low boiling and high-boiling fractions, returningsaid high-boiling fractions to the first mentioned heating coil forfurther conversion, subjecting said low-boiling fractions to furtherconversion under independently controlled temperature and pressureconditions in a separate heating coil, and introducing at least aportion of the resulting heated products into the reaction chamber.

6. A process such as claimed in claim 5 wherein the remainder of theheated products from the last mentioned heating coil is introduced intothe coking chamber.

JACQUE C. MORRELL.

